The invention relates to a method of launching a catapult, the method comprising: generating a launching force by means of a launching device; keeping a carriage immovable by means of a locking device at a launching position of the catapult; directing the launching force to the carriage, which is movable from the launching position to a releasing position guided by a body of the catapult; releasing the locking device at a launching moment, whereby the carriage moves towards the releasing position at an accelerating speed by the action of the launching force; and sending off an aircraft arranged in the carriage to the air at the releasing position.
The invention further relates to a catapult for launching an unmanned aircraft and comprising: an elongated body, a launching position being provided on a portion of a first end thereof, and a releasing position being provided on a portion of a second end thereof; a carriage movable from the launching position to the releasing position and back, and the carriage comprising fastening members for supporting the aircraft; a launching device configured to generate a launching force for accelerating the carriage in a launching direction from the launching position to the releasing position; and at least one locking device for keeping the carriage at the launching position and for releasing it at a launching moment.
The invention still further relates to a locking device for a catapult, comprising: at least one locking piece configured to pivot around a joint towards a launching direction and towards a returning direction of the catapult; a connecting member provided in the locking piece, and to which connecting member a carriage comprised by the catapult is connectable before a launch and from where it is released after the launch.
A catapult can be used for launching a light unmanned aircraft, such as a drone, a surveillance plane or a missile to the air. The catapult typically comprises a carriage to which the aircraft is fastened and which carriage is catapulted at a high speed in such a manner that the aircraft obtains a controlled starting speed and direction for takeoff. The carriage can be moved for instance by means of a pneumatic or hydraulic cylinder, which is connected to act on the carriage by means of a wire or the like. Before being launched, the carriage can be kept in place by means of a locking device. At the same time, a maximum force is directed to the carriage. After the launch, the locking device releases the carriage, i.e. the force keeping the carriage in place is suddenly suppressed. Measurements have shown that the acceleration of the carriage is not even and controlled, but that immediately after the launch, the carriage is subjected to an acceleration peak or several peaks, which may even be followed by oscillation of acceleration. Acceleration peaks may exceed the maximum allowed acceleration value of the aircraft to be launched and may damage it.